This invention relates generally to a simplified and effective process for the production of dried, high purity amino acids, which comprises depyrogenation and spray drying procedures. More specifically, chemically and physically homogeneous, rapidly dissolving products can be formulated which comprise one or more amino acids and which may further comprise salts, buffers, carbohydrates, lipids and/or micronutrients. The products formed by this process are particularly well suited for use in parenteral (intravenous) or enteral (oral or tube) nutritive supplement therapy.
Blends of amino acids find wide use as nutritive supplements. This type of nutritive therapy may be used for general nutritional enhancement, or may be designed to meet specific needs, such as the facilitation of post-operative wound healing or as an adjunct to the treatment of kidney disease, burns or trauma. For example, U.S. Pat. No. 3,697,287 (Winitz) discloses a composition palatable to humans which contains all of the essential amino acids, essential minerals and carbohydrate; U.S. Pat. No. 4,003,992 (Beigler et al.) and U.S. Pat. No. 4,279,917 (Takami et al.) disclose nutritionally acceptable amino acid solutions for intravenous administration. Parenteral and enteral nutritional supplements are subject to manufacturing standards and regulations of the Federal Drug Administration (FDA). Regulation of the manufacture of products for parenteral use is particularly stringent in terms of purity, sterility, formulation, etc. The regulations, which are strictly enforced, cover all aspects of processing, sampling, analysis and packaging. Products for enteral use must be produced by FDA-approved Good Manufacturing Practices (GMPs).
Conventional methods of formulating and packaging dried amino acids or blends thereof comprise the following series of process steps: Typically, an individual amino acid is dissolved in water, the solution is depyrogenated by ultrafiltration and the amino acid is crystallized from the solution. The crystals are removed by centrifugation, washed and dried to yield a single amino acid component. The dried, crystalline material may then be stored or physically blended with other amino acids, each prepared by the same series of steps. Each of these steps must be conducted in a sterile, or clean room, environment.
In addition to the costly and burdensome requirements for conducting these procedures in a sterile environment, significant quantities, i.e., 10 to 20%, of amino acids are lost by the use of conventional crystallization techniques. For example, somewhat less than 100%, i.e., about 85 to 95%, of the amino acid typically is recovered from the solution in crystalline form. Moreover, the solubility of the amino acid causes additional loss of product when the crystals are washed.
When intended for parenteral use, blends of crystalline amino acids generally are redissolved by a pharmaceutical company in water-for-injection, along with any other components, such as lipids or micronutrients, which are desired in the final preparation. The solution is loaded directly into intravenous bottles or the like, which are capped and terminally sterilized. Thus, it is bottles of sterile intravenous solutions which are shipped to and which must be stored by the hospitals, clinics and nursing homes which use them. Enteral products may be delivered in sterile packets for dissolution at the site of administration, or in sterile packets or containers of pre-dissolved product.